The present invention relates generally to a magnetic component including an electrically conductive winding for an electronic circuit. More particularly, the present invention relates to a bobbinless transformer having a coiled primary winding and a secondary winding forming an annular disk.
Magnetic components such as transformers are known in the art. Conventional transformers typically include a primary winding having multiple turns of a conductive wire. In the prior art, the individual turns are typically wound around a bobbin structure. The bobbin structure provides support for the shape of the primary winding. The bobbin structure of conventional transformers often includes a hollow void extending along the longitudinal axis of the bobbin structure, and a magnetically permeable core is positioned in the hollow void.
Advances in electronic and magnetic component design and fabrication have led to electronic circuits having reduced size. Bobbin-wound transformers are often the largest components in an electronic circuit. Bobbin-wound transformers occupy relatively large amounts of space in circuit layouts, as compared to other circuit components, at least in part because the bobbin structure must be accommodated on the circuit board. Also, magnetic components using bobbin-wound windings must include additional structure to accommodate and support the bobbin.
One conventional type of primary winding found in the prior art includes an elongated electrical conductor wound numerous times around a bobbin in overlapping layers. The conventional winding includes a first end initially positioned on a bobbin structure and a second end wound in several layers over the first end. Because the first end extends from an inner loop of the winding nearest the bobbin, a clearance region must exist for the first end to pass from the inner loop to the outer loop for connection to an electrical terminal. Passing the first end from the innermost layer creates requires additional space and material on the magnetic component, increasing size and cost.
In many applications it is desirable to have a transformer including multiple primary windings connected in series and separated by gaps with multiple single-turn secondary windings positioned in the gaps. Prior art transformers having this configuration typically include a bobbin around which the multiple primary windings are wound. The bobbin structure increases the overall size of the transformer.
What is needed, then, is a bobbinless transformer having a primary winding formed without using a bobbin structure to provide shape or support to the winding. Also needed is a low-profile disk-shaped secondary winding for use with the bobbinless primary winding. Additionally, methods of forming the primary and secondary windings are needed.